The Greek government is forcing employees of a state electricity utility company back to work by issuing a "civil mobilisation decree" usually reserved for national emergencies.
Public Power Corporation unions launched rolling 48-hour strikes on Thursday in protest at plans to privatise the company, forcing it to resort to short regional blackouts. The strikers have taken several production units off the grid.
A lower Athens court found the strike "illegal and abusive" on Friday.
Striking PPC employees will be served mobilisation papers this weekend. Those who refuse to report to work can be dismissed.
Greece's international creditors have demanded the sale of PPC, which involves carving out a new subsidiary accounting for about 30% of PPC's output, and selling it to private investors.